What I am confused about is why do bubbles of air in water move up. I understand why solids and liquids would move up in water if they are less dense. I get the idea that the deeper you go in water the more pressure there is because of the more water weighing down on the water and so there would be a pressure difference between the top and bottom of any object in water and because pressure * area is force there would be a force difference and this would cause a net upwards force and if this net upwards force is larger than gravity than he object would move up. I get how this mechanism works. My problem is with air specifically. What I imagine should happen is the water should collapse into the air. The way I imagine it is that air has lots of molecules freely moving about but to me this should allow water to because of gravity and pressure move into the air where the air molecule isn't present and eventually collapse into it. Even if the air molecules are fast enough and random enough that they are able to prevent such a collapse from immedietly happening I do not see how it would move up. As the force exerted on the air molecules in the bottom shouldn't be translated to the air molecules at the top. Because to my knowledge it is hard for two air molecules to hit each other. so the air should simply be squished in until it does disolve rather than moving upwards. I just can't understand how air can displace water a much denser substance to move upwards. Furthermore the water and the air should be around the same temperature. While some other things go into temperature as well other than speed it shouldn't be so easy for air to keep striking the water molecules away to prevent them from collapsing into the air. I tried my best in expressing what I found confusing but it might not have been very clear. if anyone wants me to I can definitely elaborate. Thanks for anyone's help on this.